ABB Relion SAM600, Communication Protocol Manual

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IEDs, then the alternate port (backup link) will be placed between IED3 and IED4 (for representation
and this depends on the configuration).
If any of the link breaks in the loop, then the backup link will be activated. For example, if a link
between IED1 and IED2 fails, then the backup link is activated; IED2 and IED3 will continue to
receive messages from IED4.
IED1 IED1 IED2 IED2 IED3 IED3 IED4 IED4
Sw1, root bridge Sw2
Main link
Backup link
IEC21000008 V1 EN-US
Figure 16: Ring topology, single ring
In the topology shown in Figure 17 , there are three rings, Sw1 to Sw4 form one ring, Sw1- Sw2- IED4
to IED1 forms the second ring, Sw3-Sw4-IED8 to IED5 forms the third ring. If the root port is Sw1 and
if the priority of other switches is lesser than that of the IEDs, then the alternate port or the backup
link could be between Sw3 and Sw4, IED3-IED4, IED7-IED8 (for representation and this depends on
the configuration).
IED IED IED IED IED IED IED IED
Sw1, root bridge Sw2
Main link
Backup link
IED IED IED IED IED IED IED IED
Sw3 Sw4
IEC21000006 V1 EN-US
Figure 17: Ring topology, three rings
In the topology shown in Figure 18 , there are five rings. Sw1 to Sw4 forms one ring, Sw1-Sw2-IED4
to IED1 forms the second ring, Sw1-Sw2-IED8 to IED5 forms the third ring, Sw3-Sw4-IED12 to IED9
forms the fourth ring, and Sw3-Sw4-IED16 to IED13 forms the fifth ring. If the root port is Sw1 and if
the priority of other switches is lesser than that of the IEDs, then the alternate port or the backup link
could be between Sw3 and Sw4, IED3-IED4, IED7-IED8, IED11-IED12, IED15-IED16 (for
representation and this depends on the configuration).
1MRK 511 441-UEN Rev. C Section 8
Rapid spanning tree protocol (RSTP)
Switchgear control unit SAM600-IO 39
Communication protocol manual
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